Electromagnetic relay construction



April 24, 1934. F. w. GoDsEY, JR

ELECTROMAGNETIC RELAY CONSTRUCTION Filed Aug. 25, 1932 INVENTOR ocse y,ATTORNEYS ze# f Patented Apr. 24, 1934 UNITED STATES PATENTl oFFICEFrank W. Godsey, Jr., signor to The Safety New Haven, Conn., as- CarHeating & Lighting Company, a corporation of New Jersey ApplicationAugust 25,

14 Claims.

This invention relates to the construction of electromagnetic relays andmore particularly to the construction and operation of polarizedelectromagnetic relays.

One of the objects of this invention is to provide a relay constructionof the above-mentioned character which will be simple and inexpensive,compact and rugged, and highly efficient in action. Another object is toprovide a polarized electromagnetic relay in which the many and variousdisadvantages, deficiencies and defects of polarized relay constructionsheretofore known may be dependably and reliably overcome in a thoroughlypractical, inexpensive and simple Way. Another object is to provide apolarized relay construction of high efficiency. Another object is toprovide a construction of the above-mentioned character capable of highsensitivity of action. Another object is to provide a construction ofthe above-mentioned character in which high sensitivity will be achievedat an erliciency heretofore unknown in electromagnetic relays. Otherobjects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction,combinations of elements, and arrangements of parts as will beexemplified in the structure to be hereinafter described and the scopeof the application of which will be indicated in the following claims.

In the accompanying drawing in which are shown by way of illustrationseveral of the various possible embodiments of my invention,

Figure l is a schematic front elevation of a preferred form of polarizedrelay construction, certain illustratively related parts beingd'agrammatically indicated;

Figure 2 is a horizontal sectional View as seen along the line 2-2 ofFigure l;

Figure 3 is a schematic front elevation illustrating another possibleform of polarized relay construction, certain illustratively relatedparts being diagraminatically indicated; and

F. gure 4 is a horizontal sectional View as seen along the line 4--4 ofFigure 3.

Similar reference characters refer to similar parteJ throughout theseveral views of the drawing.

As conducive to a clearer and more ready understanding of certainfeatures of my invention, it might at this point be noted that polarizedelectromagnetic relays, in which a movable part such as an armatureintended to partake of movements the irections of which are deteriff n,

- mined by the direction of current flow through 1932, Serial N0.630,327

the energizing winding of the relay, as heretofore proposed or met with,are characterized by a number of serious defects and deiiciencies; ifsuch heretofore known relays are at all sensitive, such sensitiveness isachieved at substantial sacrifices involving the use of auxiliarysources of electrical energy for energizing, for example, a polarizingWinding, but the use of such an auxiliary source of energy subjects theconstruction to dependence upon such auxiliary source and toiiuctuations and variations in the latter, making the standard ofoperation of the relay unreliable and variable. Attempts to obviate suchdefects as well as to avoid the sacrifice of eiiiciency that isattendant upon the use of an auxiliary source have centered aboututilizing a permanent magnet to achieve the polarization, but here suchattempts have resulted in serious impairment of sensitivity, failure toimprove appreciably the eiiiciency, and other disadvantages. One of thedomina-nt aims of this invention is to provide a polarizedelectromagnetic relay kin which the many disadvantages, some of whichhave just been noted, that characterize known practice in polarizedrelay construction may be reliably and inexpensively eliminated, and inwhich materially improved standards of sensitiveness, reliablity, andefficiency may be achieved.

Referring now first to Figure l there is generally indicated at l0 apolarized electromagnetic relay construction illustratively related totwo circuits, one a controlling circuit and the other a controlledcircuit. The controlling circuit may include any device or arrangement,diagrammatically indicated at l1 and which includes any suitable sourceof electrical energy to which the relay 10 is to respond; the relay 10is provided with a Winding 12, related to a magnetic circuit to be moreclearly described hereinafter, and the Winding 12 is connected byconductors 13-14 to the arrangement or device 11 so that the winding 12is made responsive to the electrical conditions established by or in thepart 11.

The controlled circuit, which like the controlling circuit abovedescribed may be of any desired or suitable character, may,illustratively, include any suitable source of electrical energyindicated at l5, a translating device 16 to be energized or actuated bythe source 15 and a fixed contact 17 related to a movable contact 18,these parts being suitably interconnected 'to form a complete electricalcircuit as is diagrammatically indicated in Figure 1 so that the circuitof the translating device 16 is opened or closed, dependsoY ing uponWhether the contacts 17-18 are in or out of engagement with each other.

The movable contact 18 is the one that is actuated by the relay 10 andit may be related in any suitable way to be controlled or actuated bythe movable part or armature of the relay 10; purely by way ofillustration I have shown the contact 18 mounted upon and carried by thearmature 19 of the relay 10 so that the position of the armature 19 willcontrol the relation between the contacts 17-18.

The armature 19 forms part of the magnetic circuit with which the relaywinding 12 is associated. This magnetic circuit is constructed andrelated to the winding 12 and to a permanent magnet so that directionalchanges in the current energizing the winding 12 bring about anactuation and corresponding change in position of the armature 19. Forpurposes of a more ready understanding of the construction and action ofthe relay, it might be assumed that the armature 19, pivoted in anysuitable way as at 20, is mechanically balanced and that its range ofmovement about the pivot 20 is between the contact 17 and a stop 21which may or may not be in the form of another contact or contacts. Thisarmature 19, made of any suitable soft iron, is to be polarized so thatchanges in the magnetic flux produced by the winding 12 will cause thearmature 19 to move from one limit of its range of movement to theother.

To polarize the armature 19 and thus to provide it with a suitablepolarizing magnetic ux, I provide a permanent magnet 22 (see also Figure2) which, however, is peculiarly related to the magnetic circuit ofwhich the armature 19 forms a part. Illustratively the member 22 maytake the form of a cylindrical piece of suitable magnet steel, such ascobalt magnet steel and about the member 22 rst relate, in any suitablemanner, a soft iron sleeve 23, the parts 22 and 23 being concentric andpreferably of identical axial length. The core 22 is permanentlymagnetized in any suitable manner.

The free or right-hand end of the armature 19 is related to and overlapsone end of this composite unit 22-23, and the magnetic circuit ispreferably completed by an L-shaped member 24-25, also of soft iron likethe armature 19 and the sleeve 23, the armature 19 being pivoted to theupper end of the vertical aim 25, as at 20, while the horizontal arm 24extends under and has secured thereto the lower end of the unit 22-23.

The Winding 12 extends about the unit 22-23 and is substantially coaxialtherewith.

By way of illustration of an illustrative construction of the parts22-23, but not by way of limitation thereto, the core 22 of cobaltmagnet steel may be given a diameter on the order of one-half inch and alength of three inches; the soft iron sleeve 23, accurately bored out toa diameter slightly less than the outside diameter of the core 22, mayhave an outside diameter of three-quarters of an inch, is then heated toexpand it and thus to receive therein the magnet steel core 22, thesubsequent cooling of the sleeve 23 shrinking the latter tightly aboutthe magnet steel core 22 and thus forming a tight and secure physicalinter-relation between the two parts. The respective end faces of theparts 22 and 23 are preferably ground of.F to lie in the same respectiveplanes. The resultant combination is then magnetized as by means of asuitably strong electromagnet, the magnet steel core 22 being thuspermanently magnetized. I have been able, with such a construction, toachieve a permanent magnetizing force in the magnet steel core 22, whichthus becomes a permanent magnet, of an order of magnitude equivalent toapproximately thirty to one hundred and fty ampere turns.

Now the permanent magnet or core 22 is of low permeability, and if italone were to be inserted in the magnetic circuit of the electromagneticwinding of the relay, as has been proposed in prior practice, theinherent low permeability thereof imposes upon the resultantconstruction the requirement of an electromagnetic winding of a high orlarge number of ampere turns; that is, the operating winding of theresultant relay must be so large that it will overcome not only thereluctance in the magnetic circuit caused by the air gap in the relaybut also the relatively very high reluctance represented by thepermanent magnet itself and which is directly in the magnetic circuit ofthe winding, resulting in a very insensitive relay construction and onewhich requires relatively large amounts of energy to achieve itsoperation.

The composite construction 22-23, however, may, in accordance with myinvention, be directly inserted in the magnetic circuit of theelectromagnetic winding 12 without incurring such vital disadvantages ashave just been noted, because the soft iron sleeve 23 is of highpermeability and hence low reluctance and is principally determinativeof the permeability of the unit 22-23 insofar as the latter forms partof the magnetic circuit.

The cross-sectional area of the sleeve 23 is proportioned, that is, madelarge enough, so that the flux from the permanent magnet 22 does notsaturate the sleeve 23, and the permanent magnet 22 therefore tends tosupply a constant amount of flux through the sleeve 23 and themagnetomotive force available across the ends of the unit is constantwithin substantially close limits and will not vary unless the soft ironsleeve 23 is saturated by the flux from the permanent magnet core 22.

The magnetomotive force thus made available by the permanent magnet 22sends a flux across the air gap (see Figure l) through the armature 19,member 25 and member 24, assuming the upper end of the permanent magnet22 to be the north pole and the lower end thereof to be the south pole;this flux, produced by the abovementioned magnetomotive force which, asalready noted above, remains constant within very close limits, is theflux which polarizes the armature 19, and it is with respect to thispolarizing iiux that the ux produced by the winding 12 acts to controlthe position of the armature 19 and hence the relation of thecircuit-controlling contacts actuated by the armature.

rPhe effective magnetic circuit in which the winding 12 functions is ofrelatively high permeability and low reluctance, being, because offeatures of construction above-mentioned, substantially unaffected bythe high reluctance and low permeability of the permanent magnet core22; the magnetic circuit available to the ux produced by the winding 12may, for purposes of better understanding certain features ofconstruction and action, be considered as including the high reluctancecore 22, the air gap, armature 19, member 25 and member 24, but the lowpermeability or high reluctance part 22 of this circuit is shunted bythe low reluctance or high permeability part 23. The magnetic circuittherefore has a portion thereof made up of two: parallel paths, namelythe parts 22 and 23. The flux produced by the winding 12 therefore seeksout and mainly passes through that path of these two parallel paths thatis of lower reluctance, and is hardly appreciably affected by the highreluctance path.

Moreover, the cross-sections of the soft iron members 19, 25 and 24 ofthe magnetic circuit may be suitably proportioned with respect to thecross-section of the soft iron sleeve 23 so as to maintain lowreluctance in so much of the magnetic circuit as they constitute.

Accordingly, it requires but a relatively small magnetomotive force orampere turns produced by the winding 12 to bring about an actuation ofthe armature 19, and the Winding 12 can cause actuation of the armature19 in response to comparatively small energizing currents. For example,when the current in the winding 12 reverses and hence when it is desiredto change the position of the armature 19 and thus alter the conditionof the controlled circuit, the magnitude of current, in the reverseddirection, through the winding 12, need be but relatively very small toproduce` the flux necessary to coact or react with the polarizing fluxin the armature 19 (produced by the permanent magnet 22) to effect thecorresponding change in position of the armature 19 itself; thereluctance of the magnetic circuit for the ux produced by such currentis consistently relatively small and is free from detrimental effectthereon by the inherent high reluctance of the permanent magnet core 22itself.

Thus, high sensitiveness is achieved and also high eniciency; neither ofthese important factors is interfered with by the low permeability ofthe permanent magnet core while efficiency is not made low because thereis no power consumption supplied by an auxiliary source of energy. Also,the many disadvantages arising out of variations in an auxiliary sourceof energy such as is necessary where the relay is electro-magneticallypolarized as in certain heretofore known structures, and thus constancyof standard of operation may be reliably achieved while at the same timeavoiding the many inherent disadvantages in heretofore known relayswhere polarization is achieved by a permanent magnet.

As illustrative of another mechanical embodiment of certain features ofmy invention, reference may be made to Figures 3 and 4 in which thecontrolling and controlled circuits are interrelated by a relayconstruction which embodies the same pivoted armature 19 as in Figure 1related to parts which complete the magnetic circuit or circuits asfollowsz-Thus, the armature 19 may be pivoted as at 20 to the verticalarm 27 of a soft iron frame-like structure 28 which has a bottom orhorizontal arm 29 extending to the right from the lower end of the arm27, whereupon it extends upwardly to form an arm 30 at whose upper endit is then extended toward the rleft to form an arm 31 that terminatesunderneath the free end of the armature 19, the frame 27 thus formingwith the armature 19 a complete magnetic circuit, all of soft iron andhence of high permeability and low reluctance. Fitted and seated betweenthe upper and lower arms 31 and 29 of the frame 28 is a member 32 madeof a material similar to the steel of which the core 22 of Figures 1 and2 is made, and the member 32 is permanently magnetized in any suitableway.

About the vertical arm 30 of the soft iron frame 28 is the winding orcoil 12 which will thus be seen to be directly related to theabove-described low reluctance magnetic circuit.

low permeability, is shunted by the upper arm 31 of the soft iron frame28, the vertical arm 30 and the portion 29L of the lower arm 29. Thedimensions and cross-sections of the permanent magnet core 32 and itsabove-mentioned soft iron shunt are so proportioned that the desiredmagnetomotive force, commensurate with that which is available acrossthe ends of the unit 22-23 of Figures 1 and 2, is available at the endsof the shunted permanent magnet 32; this magnetomotive force permanentlypolarizes the armature 19, sending a polarizing fiux therethrough in acircuit which, assuming that the north pole of the permanent magnet 32is its upper end, will be seen to extend across the air gap (with thearmature 19 in its uppermost position), through the armature 19, arm 27of the frame 28, portion 29b of the bottom arm 29, and thence to thelower end of the permanent magnet 32.

Though the permanent magnet core 32 is present in the apparatus, itshigh reluctance is virtually prevented from interfering with the highefficiency and high sensitiveness of operation of the relay; whatevercurrents energize the winding 12 (Figure 3) produce an electromotiveforce or Iiux which has available to it a magnetic circuit of highpermeability and hence low reluctance, in spite of the contrarycharacteristics of the permanent magnet core 32, and this magneticcircuit will be seen to include the parts 39, 29, 27, armature 19, andpart 31, all of which may be made of high permeability material. Thismagnetic circuit will be seen to have a by-pass of low reluctance aboutthe high reluctance core 32 or, stated differently, the flux induced bythe winding 12 and flowing along the arm 30 of the frame 28 hasavailable to it two paths, one of which is of high reluctance and theother of which is of low reluctance, and because of the relatively widedivergence or differences in these reluctances, the flux seeks and flowsthrough the reluctance path and is hardly appreciably affected by thehigh reluctance path in parallel therewith.

The high reluctance path is made up virtually of the permanent magnetcore 32 which, however, is shunted or has in parallel with it the lowreluctance path made up of the parts 29b and 27, and the armature 19.Thus, the ux produced by the winding 12, regardless of its direction, ismade directly to coact or react with the polarized armature 19 andbecause of the high permeability path thus made available to it, but asmall magnetomotive force or flux from the winding 12 is necessary tocause an actuation of the armature 19 and correspondingly a small amountof current or energizing energy in the winding 12 is necessary to bringabout the desired operation of the armature 19.

The high permeability parts of the relay con- The permanent magnet core32, inherently of ITS struction, two possible examples of which areabove described, are made of a suitable iron, for example Norway iron orsilicon steel, while the permanent magnet core is made of a suitablematerial adapted to be permanently magnetized,

such as tungsten steel, cobalt steel,` or the like. v/,a

Moreover, the construction lends itself to unique and advantageouscontrol; for example, with a given size of permanent core and a givenpermanent magnetization thereof, the extent of polarizing action thereofupon the armature 19 may- Y.

be predetermined in advance by suitably proportioning with respectthereto the cross-sections of the high permeability magnetic circuitswhich are shunted about the permanent magnet. For example, thecross-section of the sleeve 23 of the construction of Figures l and 2 orthe crosssection of the shunt circuit formed by the parts 31, 30 and 29aof the construction of Figures 3 and 4 may be made large or small withrespect to the strength of the permanent magnet itself according as thepolarizing iiuX in the armature 19 is desired to be small or large.These features are of great practical advantage in that, even thoughcertain circumstances of use might dictate a relatively small polarizingflux, a relatively large or strong permanent magnet might neverthelessbe employed and thus achieve greater or more lasting permanence thanwould otherwise be possible.

It will thus be seen that there has been provided in this invention arelay construction in which the various objects hereinabove mentioned,together with many thoroughly practical advantages are successfullyachieved. It will be seen that the construction is compact andinexpensive, is highly sensitive and is of high eihciency, and is welladapted to meet the varying conditions of practical use, particularlysuch conditions where but a small amount of electrical energy isavailable in the controlling circuit for energization of the relay.

As many possible embodiments may be made of the above invention and asmany changes might be made in the embodiment above set forth, it is tobe understood that all matter hereinbefore set forth, or shown in theaccompanying drawing, is to be interpreted as illustrative and not in alimiting sense.

I claim:

1. In construction of the character described, in combination, meansmade up of three parts of high permeability and arranged substantiallyin the form of a U, one of said parts being in the form of a movablearmature, and the three parts forming part of a magnetic circuit; apermanent magnet core inherently of 10W permeability substantiallyclosing the U formed by said parts, for permanently polarizing thearmature part thereof hollow means of magnetic material of highpermeability surrounding said core and extending lengthwise thereof andforming a magnetic shunt about said core for by-passing some of the iluxof the latter; and a control winding about said last-mentioned means,said control winding having thereby a complete magnetic circuit of highpermeability, whereby the iiux produced by said winding avoids having tobe forced through said low permeability core.

2. In construction of the character described, in combination, meansmade up of three parts of high permeability and arranged substantiallyin the form of a U, one of said parts being in the form of a movablearmature, and the three parts forming part of a magnetic circuit; apermanent magnet core inherently of low permeability substantiallyclosing the U formed by said parts, for permanently polarizing thearmatiue part thereof; hollow means of magnetic material of highpermeability surrounding said core and forming a magnetic shunt aboutsaid core for by-passing some of the of the latter and extendinglengthwise of said core to a sufficient extent to substantially closethe U formed by said firstmentioned three parts to form with the lattera complete magnetic circuit which thus is of high permeability; and acontrol winding related to said complete magnetic circuit for sendingtherethrough a flux the direction of which changes with directionalchanges of current energizing said winding, said control winding havingthereby a complete magnetic circuit of high permeability, whereby theiiux produced by said winding avoids having to be forced through saidlow permeability core.

3. In construction of the character described, in combination, meansmade up of three parts of high permeability and arranged substantiallyin the form of a U, one of said parts being in the form of a movablearmature, and the three parts forming part of a magnetic circuit; apermanent magnet core inherently of low permeability substantiallyclosing the U formed by said parts, for permanently polarizing thearmature part thereof a sleeve made of a magnetic material of highpermeability and surrounding said core and forming with saidfirst-mentioned three parts a complete magnetic circuit of highpermeability; and a control winding related to said high permeabilitymagnetic circuit for creating therein a flux whose direction changeswith directional changes in current energizing said Winding.

4. In construction of the character described, in combination, meansmade up of three parts of high permeability and arranged substantiallyin the form of a U, one of said parts being in the form of a movablearmature, and the three parts forming part of a magnetic circuit; apermanent magnet core inherently of low permeability substantiallyclosing the U formed by said parts, for permanently polarizing thearmature part thereof; a sleeve made of a magnetic material of highpermeability and surrounding said core and forming with saidnist-mentioned three parts a complete magnetic circuit of highpermeability; and a control winding about said sleeve connected to acircuit in which the direction of current flow changes, for sendingthrough said high permeability magnetic circuit a iiux directionallyresponsive to directional changes in the current energizing saidwinding.

5. In construction of the character described,

in combination, a relay having a movable armature and a permanent magnetcore for passing through said armature a polarizing flux, said corebeing inherently of high reluctance; a control winding for producing ailux through said armature in a direction depending upon the directionof current flow through the winding; and means forming a low reluctancepath for the flux produced by said winding, said means and said corebeing related in parallel whereby the iiux from said winding isby-passed around said high reluctance core, whereby saidelectro-responsive means need be less powerful than would otherwise bethe case.

6. In construction of the character described, in combination, a relayhaving means of magnetic material of relatively high permeability and apermanent magnet core that is inherently of relatively low permeabilityforming With said means a complete magnetic circuit, Whereby said meansis polarized by flux from said permanent magnet core; electro-responsivemeans for producing a magnetic ux in said rst-mentioned means forcoaction with said iiux from said permanent magnet core; and means ofrelatively high permeability for shunting the flux produced by saidelectro-responsive means around the said relatively low permeabilitypermanent magnet core, whereby said electro-responsive means need beless powerful than would otherwise be the case.

7. In construction of the character described, in combination, a relayhaving means of magnetic material of relatively high permeability and apermanent magnet core that is inherently of relatively low permeabilityforming with said means a complete magnetic circuit, Whereby said meansis polarized by iiux from said permanent magnet core; electro-responsivemeans for producing a magnetic ilux in said first-mentioned means forcoaction with said ilux from said permanent magnet core; and means forreducing the energizing current of said electro-responsive meansnecessary for operation of the relay and comprising means of relativelyhigh permeability so related to said magnetic circuit and saidelectro-responsive means that the reluctance of the path through whichsaid ux produced by said electro-responsive means passes is less thanthe reluctance of said magnetic circuit.

8. In construction of the character described, in combination, means ofrelatively low reluctance forming a complete magnetic circuit andprovided with electro-responsive means for inducing in said circuitamagnetic flux; and a permanent magnet core for permanently polarizingsaid magnetic circuit, said core being embedded in a portion of said lowreluctance means and being thereby positioned so that the highreluctance path formed by said core is shunted by at least part of saidrelatively low reluctance magnetic circuit.

9. In construction of the character described, in combination, means ofrelatively low reluctance forming a complete magnetic circuit andprovided with electro-responsive means for inducing in said circuit amagnetic flux; and a permanent magnet core means for permanentlypolarizing said magnetic circuit, one of said magnetic means beingsubstantially embedded in the other whereby said core means ispositioned so that the high reluctance path formed by said core means isshunted by a plurality of portions of said relatively low reluctancemagnetic circuit, whereby the high reluctance of said permanent magnetcore has but an inappreciable effect upon the reluctance of saidmagnetic circuit.

10. In construction of the character described,

in combination, an armature of magnetic material, a permanent magnetcore inherently of relatively high reluctance for inducing in saidarmature a polarizing flux, a winding for inducing a flux in saidarmature for coaction with said polarizing fiux, and means of relativelylow reluctance coacting with said Winding and said armature forby-passing the flux induced by said Winding around said relatively highreluctance core, at least a portion of said means lying lengthwise alongsaid core in the direction of the passage of flux therethrough.

1l. In construction of the character described, in combination, means ofmagnetic material forming magnetic circuits and comprising twosubstantially parallel but spaced means of relatively high permeabilityhaving three members substantially bridged thereacross, thereby to forma plurality of individual magnetic circuits in shunt relation to eachother, one of said members being in the form of a permanent magnet coreof relatively low permeability and the remaining two members being ofrelatively high permeability, one of said members being substantially inthe form of a tube and another of said members passing through the tube,and a Winding about one of said relatively high permeability members.

12. In construction of the character described, in combination, apolarized relay having a winding, an armature, and a permanent magnetcore for inducing in said armature a polarizing flux, said core beinginherently of relatively low permeability; and means of relatively highpermeability shunting the flux induced by said winding around saidrelatively low permeability core, said winding extending about both saidcore and said means.

13. In construction of the character described, in combination, apermanent magnet member and a low reluctance shunt member therefor, oneof said members being in the form of substantially a tube and the otherof said members being accommodated within said tube.

14. In construction of the character described, in combination, apermanent magnet member and a low reluctance shunt member therefor, saidshunt member being in the form substantially of a sleeve shrunk onto thepermanent magnet member.

FRANK W. GODSEY, JR.

